The invention relates to a method and apparatus for determining the distance to an archery target.
The use of bow and arrow for game hunting or target shooting is one of the most popular recreational activities throughout the world. Indeed, more than $1 billion is spent each year on purchases of bows alone. In shooting beyond distances of approximately 15 yards, which is almost always required in game hunting, the accuracy of the shot is dependent upon the ability of the archer to adjust the drop of the arrow due to gravity. A skilled archer can accurately hit target distances within approximately 50 yards.
Several techniques have been employed in the past for aiding in effecting the required compensation. The most popular technique employs pins which are spaced apart on the bow. In theory, for a particular type animal such as a deer, the bow angle will be correct when a particular set of two pins are exactly bracketed by the back and belly of the animal. This technique is, however, extremely rough since it presupposes that animals are of the same size and that the pull of each hunter on the string will be the same. Manual optical stereoscopic sights such as used for hunting with guns have also been employed. Such sights are in practice too slow and cumbersome to be of benefit in archery hunting.
The present invention relates to a unique apparatus adapted for mounting on the bow for providing accurate indication to the hunter of the distance to a target. Once the hunter knows the exact distance to the target, he can readily determine from experience or written instructions what angle to the horizontal should be employed for a given pull of the string.
This is achieved by directing a beam of collimated light, preferably coherent radiation from a small solid state laser, to the target so that, when the bow is aimed at a target, light reflected from the target is received by a linear photosensitive element which produces an output indicating the position of the incident radiation in a linear direction. The element and laser are mounted so that the position along the element indicates the distance to the target. Appropriate circuitry is further provided to determine that distance and preferably to digitally display the same to the hunter.
Other objects and purposes of the invention will be clear from the following detailed description of the drawings.